Method of, and apparatus for, de-icing an aircraft by infrared radiation

ABSTRACT

An improved apparatus (11) for emitting infrared radiation of a desired wavelength includes a primary surface (.[.35.]. .Iadd.25.Iaddend.); a burner (24) for raising the temperature of the primary surface so as to cause the primary surface to emit infrared radiation of a first wavelength; a secondary surface (26) surrounding the primary surface in spaced relation thereto and arranged to be heated by infrared radiation emitted by the first surface and for emitting infrared radiation of a second wavelength toward the object; and an actuator (28) for selectively varying the spacing between the primary and secondary surfaces so that infrared radiation emitted by the secondary surface .[.will be at a desired wavelength and.]. will be focused; whereby the apparatus will emit infrared radiation of a desired wavelength toward the object. The improved apparatus may be used in a method of de-icing a portion of an aircraft, which includes the steps of: providing a structure (10) having an infrared heater (23); moving an aircraft relative to the structure to a position adjacent the heater; operating the heater so as to emit radiation toward the object; and controlling the wavelength of radiation emitted by the heater; thereby to melt snow and ice from the aircraft portion.

This is a continuation of copending application Ser. No. 08/020,216,filed on Feb. 19, 1993, now abandoned.

TECHNICAL FIELD

This invention relates generally to the field of methods of, andapparatae for, de-icing portions of an aircraft on the ground, and, moreparticularly, to an improved method and apparatus for de-icing anaircraft by means of a focusable, variable-wavelength infrared energysource.

BACKGROUND ART

It is sometimes necessary to de-ice certain portions of an aircraftprior to take-off.

Existing technology in common use today involves the spraying of largequantities of chemicals onto the working surfaces (e.g., wings, rudder,ailerons, flaps, stabilizers, etc.) of the aircraft. These chemicals arenormally applied just prior to the aircraft's departure from theboarding gate Federal requirements dictate a maximum time intervalbetween application of the de-icing spray and take-off. This timeinterval is usually on the order of from about fifteen to about thirtyminutes. Unfortunately, with the traffic jams common at some majorairports, the departure interval is often extended beyond thatrecommended. If this occurs, the plane must sometimes be de-iced asecond time before take-off. The desire to maintain establishedschedules and to minimize costs makes this second step undesirable, evenif needed. The presence of ice and snow on airfoil surfaces duringtake-off has been indicated as the probable cause of many crashes.

The foregoing, when considered along with soon-to-be-enforced stricterenvironmental regulations concerning the handling, storage, use andcollection of over-sprayed de-icing chemicals, establishes a presentneed to find a better way to remove accumulations of ice and snow inpreparation for take-off.

Two types of de-icing chemicals are in use today. The United Statestypically uses Type I, which is a mixture of ethylene glycol orpropylene glycol and water. This mixture is heated to about 140°-180°F., and then sprayed on the aircraft. European countries commonly useType II. This is a blend of glycol and a thickening agent, which createsa thicker jelly-like substance. The Type It mixture does hold longer,but can affect take-off of small aircraft. Hence, it is not recommendedfor use on aircraft having rotation speeds of less than about 85 knots.

It has been proposed that all U.S. airport de-icing equipment bemodified to use European Type II chemicals. However this hasshortcomings. Upon information and belief, propylene glycol isconsidered safe to humans by the Food and Drug Administration, but isharmful to the environment. While not currently regulated by OSHA, ithas been reported to cause skin irritation, and is listed as a hazardousair pollutant in the Clean Air Act Amendments of 1990. Ethylene glycolis poisonous to humans, and is regulated by OSHA because of a risk ofthroat and respiratory tract irritation. The Water Quality Act of 1987prohibits the discharge of polluted water into navigable waters andregulations have been promulgated to prevent airports from dumping ordischarging glycol-contaminated storm water run-off into rivers andsewer systems.

Accordingly, there is believed to be a clear and present need for animproved method of, and apparatus for, de-icing portions of an aircraftwithout the need of such de-icing chemicals.

DISCLOSURE OF THE INVENTION

This invention provides an improved method of, and apparatus for,de-icing portions of an aircraft without the need of such hazardouschemicals.

In one aspect, the invention broadly provides an improved method ofdeicing a portion of an aircraft, comprising the steps of: providing astructure having an infrared heater; moving an aircraft relative to saidstructure to a position adjacent said heater; operating said heater soas to emit infrared radiation toward said aircraft portion; andcontrolling the wavelength of the radiation emitted by said heater,thereby to melt ice and snow from said aircraft portion.

In another aspect, the invention provides an improved apparatus forde-icing portions of an aircraft by a controllable radiant energytechnique. The improved apparatus is arranged to emit infrared radiationof a desired wavelength toward an aircraft having a undesired substance(e.g., ice, snow, water) thereon. The improved apparatus broadlycomprises: a primary surface (25); a heater or burner (24) for raisingthe temperature of the primary surface so as to cause the primarysurface to emit infrared radiation of a first wavelength; a secondarysurface (26) surrounding the primary surface in spaced relation theretoand arranged to be heated by infrared radiation emitted by the firstsurface and for emitting infrared radiation of a second wavelengthtoward the aircraft; and an actuator (28) for selectively varying thespacing between the primary and secondary surfaces so that thewavelength of the infrared radiation emitted by the secondary surfacewill be at the wavelength determined by the design relationship betweenthe primary and secondary surfaces; whereby the apparatus will emitinfrared radiation of a desired wavelength toward the aircraft. In thepreferred embodiment, the wavelength of the radiation emitted toward theaircraft is the wavelength of maximum absorptivity of thesubstance-to-be-removed.

Accordingly, the general object of the invention is to provide animproved method of de-icing portions of an aircraft prior to take-off.

Another object is to provide improved apparatus for de-icing portions ofan aircraft prior to take-off.

Another object is to provide an improved method of, and apparatus for,de-icing portions of an aircraft by a radiant infrared technique, and byavoiding the use of potentially hazardous de-icing chemical in commonuse today.

Still another object is to provide an improved method of, and apparatusfor, heating a distant object by means of emitted infrared radiation.

These and other objects will become apparent from the foregoing andongoing written specification, the drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of a preferred sequence of manipulative stepsinvolved in practicing the improved method to de-ice an aircraft.

FIG. 2 is a top plan view of a drive-through structure containing aplurality of infrared heaters, with the roof of the structure removed,and showing the array of heaters relative to two aircraft positions.

FIG. 3 is the front elevational view of the drive-through structureshown in FIG. 2.

FIG. 4 is a fragmentary vertical sectional view of one of the heaters,showing the surrounding skirt as being in one position relative to theburner.

FIG. 5 is a fragmentary vertical sectional view of one of the heaters,showing the surrounding skirt in another position relative to theburner.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

At the outset, it should be clearly understood that like referencenumerals are intended to identify the same structural elements, portionsor surfaces consistently throughout the several drawing figures, as suchelements, portions or surfaces may be further described or explained bythe entire written specification of which this detailed description isan integral part. Unless otherwise indicated, the drawings are intendedto be read (e.g., arrangement of parts, mounting, etc.) together withthe specification, and are to be considered a portion of the entirewritten description of this invention. As used in the followingdescription, the terms "horizontal", "vertical", "left", "right", "up"and "down", as well as adjectival and adverbial derivatives thereof(e.g., "horizontally", "rightwardly", "upwardly", etc.) simply refer tothe orientation of the illustrated structure as the particular drawingfigure faces the reader. Unless otherwise indicated, the terms"inwardly" and "outwardly" refer to the orientation of a surfacerelative to its axis of elongation, or axis or rotation, as appropriate

Turning now to the drawings, the present invention provides an improvedmethod of, and apparatus for, heating a substance by means of emittedinfrared radiation. In one application, the method and apparatus areused to de-ice an aircraft.

Referring now to FIGS. 1-3, an aircraft to be de-iced is driven throughan open-ended structure, generally indicated at 10, having a pluralityof overhead infrared heaters, severally indicated at 11 arranged in arectangular array. In FIG. 2, two aircraft positions are indicatedwithin the structure. The first is indicated at 12, and the second isindicated at 13. These two positions have been omitted from FIG. 3 inthe interest of clarity.

As best shown in FIG. 1, the aircraft first enters the drive-throughde-icing structure 10, as indicated at block 14 in FIG. 1. Upon entry tothat structure and/or when in the position of aircraft 12, as much ice,snow and/or water as can be removed are physically removed. This isindicated in block 15 in FIG. 1. The means for physical removal mayinclude an air curtain, or the like. After as much of the adherentsubstance as can be physically removed has been removed, the aircraftthen advances forwardly toward the second station, indicated by aircraftposition 13. This step is indicated in block 16 of FIG. 1. Assuming thatthe type of aircraft is known, selected heaters are then operated toemit radiation. The particular heaters which may be operated may bedetermined either from the known type of the aircraft (i.e., having aknown shape), or by proximity sensors (not shown) acting downwardly andoperatively arranged to sense portions of the aircraft therebeneath.This latter step is indicated by block 18 in FIG. 1. In any event, onlythose heaters which are aimed downwardly at portions of the aircraft areoperated. Those heaters which are operated are selectively focused toemit radiation to maximize energy .[.of.]. .Iadd.on .Iaddend.the surfaceof the aircraft .Iadd.as .Iaddend.needed to melt ice or snow. This isindicated by blocks 19 and 20 in FIG. 1. The various heaters .[.areoperated so as to.]. emit radiation toward the aircraft at a wavelengthwhich coincides with the wavelength of the maximum absorptivity of thesubstance to be removed. In any event, after the adherent substanceshave been melted, the aircraft is then dried, as indicated in block 21of FIG. 1. The aircraft may be dried under the influence of heat with orwithout an accompanying air curtain. Thereafter, de-icing chemicals areapplied to the now-dry aircraft (as indicated at 22 in FIG. 1), and theaircraft then exits the de-icing structure (as indicated at 23 of FIG.1), taxis to the runway, and is ready for take-off.

FIG. 4 is a fragmentary vertical sectional view of one of the heatersshown in FIGS. 2 and 3. This heater apparatus, generally indicated at11, broadly includes a burner 24 operatively arranged to heat afrusto-conical primary surface 25, a secondary surface 26 surroundingthe primary surface in spaced relation thereto, and an actuator 28operatively arranged to selectively vary the spacing between the primaryand secondary surfaces. The heater or burner 24 is shown .[.is.]..Iadd.as .Iaddend.including a control housing 29 having adownwardly-directed burner head 30 arranged concentrically within anelongated vertical tube 31. Thus, a flame emitted by burner 24 willtravel down the tube and be discharged through the lower open end 32thereof toward a dish-like layer of insulation 33 arranged on the upperside of a wall 34. The heat of combustion will then heat primary surface25, and will flow upwardly through the annular space between inner tube31 and outer tube 35, and be vented through a lateral opening 36. Thesecondary surface 26 is shown as being frusto-conical in shape, and hasa downwardly-facing annular horizontal portion 38 at its upper end. Theentire secondary surface 26,38 is insulated, as indicated at 39.Actuator 28 has a body or housing 40 mounted on the control housing, andhas a rod portion 41 connected to the insulated secondary surface.Actuator 28 may be selectively operated to move rod 41 either upwardlyor downwardly, as desired. Such operation of the actuator effectivelyvaries the spacing between the primary and secondary surfaces, andchanges the output concentration and focal distance.

In operation, a conventional gaseous fuel is supplied to the burner, andis ignited. The burner then issues a downwardly-directed flame againstinsulation 33. The flame then rolls reversely and rises upwardly to heatprimary surface 25. The heat of combustion travels upwardly through theannular chamber between the inner and outer tubes 31,35, and is thenvented via lateral opening 36. Thus, the heater raises the temperatureof the primary surface 25, and causes .[.it.]. .Iadd.that heat exchanger.Iaddend.to emit infrared radiation. The temperature of the primarysurface may be on the order of 2,000° F. The infrared radiation emittedby the primary surface is directed toward the secondary surface andraises .[.its.]. .Iadd.that heat exchanger's .Iaddend.temperature. Thetemperature of the secondary surface 26 is, therefore, less than that ofthe primary surface, and may typically be in the range of about900°-1,000° F. The secondary surface then emits infrared radiation of adesired wavelength downwardly toward the aircraft therebeneath. Thus,the primary surface radiates infrared energy to heat the secondarysurface, which in turn emits radiation toward the object. .[.The spacingbetween the primary and secondary surface determines the temperature ofthe secondary surface, for a constant-temperature primary surface..].

One unique feature of the invention is that the actuator 28 isselectively operated so as to vary the spacing between the primary andsecondary surfaces so that the secondary surface will emit infraredradiation of a desired energy pattern.

In the preferred embodiment, .[.this.]. .Iadd.the .Iaddend.desiredwavelength is the wavelength of the maximum absorptivity of thematerial-to-be-removed (e.g., ice, snow or water). Thus, the apparatusmay be tuned to emit radiation at the desired wavelength by selectivelyvarying the design between the primary and secondary surfaces.

FIG. 4 depicts the depending cupshaped skirt having the secondarysurface as being in one position relative to the burner, and FIG. 5simply depicts such skirt as being in a lowered position relative to thebody. This is simply to illustrate the difference in spacing between theprimary and secondary surfaces.

MODIFICATIONS

The present invention contemplates that many changes and modificationsmay be made. While it is presently preferred to use the apparatus toselectively de-ice aircraft, the person skilled in this art will readilyappreciate that the improved method and apparatus could, alternatively,be used to simply heat an object. Accordingly, this alternative useshould not be excluded from the scope of the claims unless an expresslimitation to the effect appears therein.

The improved method may include a greater or lesser number of steps thanthose shown in FIG. 1. Similarly, the structure of the apparatus maydiffer from that shown in FIGS. 4 and 5. For example, the primarysurface 25 need not be frusto-conical, but could be convex or arcuate,as desired. Similarly, the outer tube 35 could be tapered upwardly so asto provide a progressive flow restriction, all with the concomitantadvantage of also heating outer tube 35. Similarly, the invertedcup-shaped skirt which forms the body of the secondary surface need notbe of the particular form and shape shown. In other words, the secondarysurface could be arcuate, parabolic, or some other concave surface, asdesired.

Therefore, while preferred forms of the improved method and apparatushave been shown and described, and several modifications thereofdiscussed, persons skilled in this art will readily appreciate thevarious additional changes and modifications may be made withoutdeparting from the spirit of the invention, as defined anddifferentiated by the following claims.

What is claimed is:
 1. A method of de-icing a portion of an object,comprising .[.the steps of.].:.Iadd.(a) .Iaddend.providing a structurehaving a source of infrared radiation, said source including a firstmeans for emitting infrared radiation of a first wavelength and a secondmeans spaced from said first means and heated by the infrared radiationemitted by said first means for emitting infrared radiation of asecond.Iadd., predetermined .Iaddend.wavelength; .Iadd.(b).Iaddend.moving an object relative to said structure to a positionadjacent .Iadd.to .Iaddend.said source of infrared radiation; .Iadd.(c).Iaddend.operating said source of infrared radiation so as to emitinfrared radiation of said second wavelength toward the portion of saidobject to be de-iced; and .Iadd.(d) .Iaddend..[.controlling the secondwavelength of the radiation emitted by said source of infrared radiationby.]. adjusting the spacing between the first means and the secondmeans, thus controlling the .[.emitted.]. .Iadd.distribution of.Iaddend.infrared radiation .[.distribution.]. .Iadd.emitted at thesecond wavelength .Iaddend.so as to .[.maximize the absorption of.]..Iadd.concentrate .Iaddend.such radiation .[.by.]. .Iadd.on .Iaddend.anysnow and ice to be melted from said object portion; .Iadd.(e).Iaddend.thereby to provide radiant infrared energy at a high.[.output.]. .Iadd.concentration .Iaddend.and at a desired wavelength tomelt the snow and ice from said object portion.
 2. The method as setforth in claim 1, .[.and.]. further comprising .[.the additional stepof:.]. physically removing accumulations or ice and snow from saidobject portion .[.prior to the step of.]. .Iadd.before.Iaddend.operating said source of infrared radiation.
 3. The method asset forth in claim 1, .[.and.]. further comprising .[.the additionalstep of:.]. drying said object portion after ice and snow have beenmelted therefrom.
 4. The method as set forth in claim 3, .[.and.].further comprising .[.the additional step of:.]. applying an anti-icingchemical to said object portion after snow and ice have been meltedtherefrom.
 5. The method as set forth in claim 1, .[.and.]. furthercomprising .[.the additional step of:.]. applying an anti-icing chemicalto said object portion after snow and ice have been melted therefrom. 6.The method as set forth in claim 1, .[.and.]. further comprising .[.theadditional step of:.]. focusing such emitted radiation distribution.Iadd.at .Iaddend.said object portion.
 7. The method as set forth inclaim 1, wherein said source of infrared radiation furthercomprises:.Iadd.(a) .Iaddend.said first means comprising a primarysurface; .Iadd.(b) .Iaddend.a heater for raising the temperature of saidprimary surface so as to cause said primary surface to emit saidinfrared radiation of said first wavelength; .Iadd.(c) .Iaddend.saidsecond means comprising a secondary surface surrounding said primarysurface in spaced relation thereto and arranged to be heated by saidinfrared radiation emitted by said primary surface for emitting saidinfrared radiation at said second wavelength toward said object;.[.and.]. .Iadd.(d) .Iaddend.an actuator for selectively varying thespacing between said primary and secondary surfaces so that saidinfrared radiation emitted by said secondary surface .[.will be.]. atsaid .[.desired.]. .Iadd.second .Iaddend.wavelength .[.and.]. will befocused.
 8. A method of heating a portion of an object, comprising.[.the steps of.].:.Iadd.(a) .Iaddend.providing a structure having aninfrared heater, a first means for emitting infrared radiation of afirst wavelength, and a second means spaced from said first means andheated by the infrared radiation emitted by said first means foremitting infrared radiation of a second wavelength; .Iadd.(b).Iaddend.moving an object relative to said structure to a positionadjacent to said heater; .Iadd.(c) .Iaddend.operating said heater so asto emit infrared radiation of said second wavelength toward the portionof said object to be heated; and .Iadd.(d) .Iaddend..[.controlling thesecond wavelength of the radiation emitted by said heater by.].adjusting the spacing between the first means and the second means, thuscontrolling the .[.emitted.]. .Iadd.distribution of .Iaddend.infraredradiation .[.distribution.]. .Iadd.emitted at the second wavelength.Iaddend.so as to maximize the absorption of such radiation by saidobject portion;thereby to heat said object portion.
 9. Apparatus foremitting infrared radiation of a desired wavelength toward an object,comprising:.Iadd.(a) .Iaddend.a primary surface; .Iadd.(b) .Iaddend.aheater for raising the temperature of said primary surface so as tocause said primary surface to emit infrared radiation of a firstwavelength; .Iadd.(c) .Iaddend.a secondary surface surrounding saidprimary surface in spaced relation thereto and arranged to be heated byinfrared radiation emitted by said primary surface and for emittinginfrared radiation of a second wavelength toward said object; and.Iadd.(d) .Iaddend.an actuator for selectively varying the spacingbetween said primary and secondary surfaces so that infrared radiationemitted by said secondary surface .[.will be.]. at .[.a desired.]..Iadd.the second .Iaddend.wavelength .[.and.]. will be focused;.Iadd.(e) .Iaddend.whereby said apparatus will emit infrared radiationof a desired wavelength toward said object.
 10. The apparatus as setforth in claim 9 wherein said primary surface is frusto-conical.[.,.].and faces away from said object.
 11. The apparatus as set forth in claim10 wherein a portion of said secondary surface is frusto-conical.[.,.].and faces toward said object.
 12. The apparatus as set forth in claim 9wherein said heater has an elongated tube, and wherein said secondarysurface is slidably mounted on said tube.
 13. The apparatus as set forthin claim 9 wherein said object is an aircraft having a substancethereon, and wherein the wavelength of infrared radiation emitted bysaid secondary surface is the wavelength of maximum absorptivity of saidsubstance. .Iadd.14. Apparatus for emitting infrared radiation of adesired wavelength toward an object, comprising:(a) a heat source; (b) afirst heat exchanger substantially surrounding the heat source andshaped and positioned relative to the heat source so as to radiate heata first wavelength when the heat source operates; (c) a second heatexchanger substantially surrounding the first heat exchanger and shapedto radiate heat at a second wavelength when the heat source operates;and (d) an actuator coupled to the first and second heat exchangers insuch a way as to controllably vary the spacing between the first andsecond heat exchanger. .Iaddend..Iadd.15. The apparatus of claim 14wherein part of the second heat exchanger is insulated, whereby heat isradiated at the second wavelength only from a portion of the second heatexchanger. .Iaddend..Iadd.16. The apparatus of claim 14 wherein thesecond heat exchanger is formed in a frusto-conical shape..Iaddend..Iadd.17. The apparatus of claim 14 wherein the first andsecond heat exchangers are shaped and relatively positioned so thatvarying the spacing between the first and second heat exchangers changesthe trajectory of at least some of the heat radiated by the second heatexchanger. .Iaddend..Iadd.18. The apparatus of claim 14 wherein thesecond heat exchanger is positioned to intercept substantially all ofthe heat radiated by the first heat exchanger. .Iaddend..Iadd.19. Amethod of de-icing an object comprising:(a) providing a structurehaving:(i) a heat source, (ii) a first heat exchanger spaced from theheat source, and (iii) a second heat exchanger spaced from the firstheat exchanger and having a shape selected to radiate heat at a selectedand desired wavelength when the heat source operates; (b) positioning anobject relative to said structure; and (c) operating the heat source,thereby heating the first heat exchanger and causing the first heatexchanger to radiate infrared radiation at a first wavelength in thedirection of the second heat exchanger, thereby causing the second heatexchanger to absorb the infrared radiation of the first wavelength andradiate infrared radiation at the desired wavelength toward the object..Iaddend..Iadd.20. The method of claim 19 wherein the object is asurface of an aircraft and wherein the desired wavelength is thewavelength of maximum absorptivity of snow and ice. .Iaddend..Iadd.21.The method of claim 19 wherein providing a structure includes using astructure wherein the first heat exchanger surrounds the heat source..Iaddend..Iadd.22. The method of claim 21 wherein providing a structureincludes using a structure wherein the second heat exchanger surroundsthe first heat exchanger. .Iaddend..Iadd.23. The method of claim 19wherein part (d) comprises causing the second heat exchanger to absorb asubstantial portion of the infrared radiation radiated at the firstwavelength by the first heat exchanger. .Iaddend..Iadd.24. A method ofde-icing an object comprising:(a) providing a structure having:(i) aheat source, (ii) a first heat exchanger spaced from the heat source,and (iii) a second heat exchanger spaced from the first heat exchangerand having a shape selected to radiate heat at a selected and desiredwavelength when the heat source operates; (b) positioning an objectrelative to said structure; (c) operating the heat source, therebyheating the first heat exchanger and causing the first heat exchanger toradiate infrared radiation at a first wavelength in the direction of thesecond heat exchanger, thereby causing the second heat exchanger toabsorb the infrared radiation of the first wavelength and radiateinfrared radiation at the desired wavelength toward the object; and (d)adjusting the spacing between the first heat exchanger and the secondheat exchanger, thus control the distribution of radiated infraredradiation. .Iaddend..Iadd.25. The method of claim 24 wherein controllingthe radiation distribution comprises focusing the radiation at theobject. .Iaddend.